Chucking mechanism



Filed Nov. las, 1940 2 Sheefcs-Sheet l l Smaentor ./.EONHRD O. CHRLSENJuly 28,l 1942.

L. O. CARLSEN CHUCKING MECHANISM Filed Nov. 18, 1940 2 Sheets-Sheet 2 2.Lnb Mm noentor LEON/GRD 0. CHLSE/V Patented July 28, 1942 Leonard 0.Carlsen, Rochester, N.

Y., assignor to Gleason Works, Rochester, N. Y., a corporation o! NewYork Application November 18, 1940, Serial No. 366,196

4Claims.

The present invention relates to hydraulic control mechanisms andparticularly to a hydraulic control mechanism such as may be employed inactuating a chuck.

One object of Ithe invention is to provide a chucking mechanism ofrelatively simple construction in which the chuck is not only releasedhydraulically but also moved to chucking position hydraulically.

A further object of the inventionris to provide a full hydraulicallyoperated chucking mechanism, which can be operated in. conjunction withother hydraulically operated parts of a machine, but in which thechucking pressure may be adjusted and predetermined in accordance withcharacteristics of the job to be/chucked. Y

Still another object of the invention is to provide a pressure reducingvalve of simple construction that may be employed with the chuckingmechanism of .the present invention or with other hydraulicallycontrolled apparatus for predetermining the operating pressure of saidchucking mechanism or apparatus.

A still further object of the invention is to provide a draw-bar typechucking mechanism which will permitA of adjusting and removing thedrawbar from either end of the Work spindle on which the chuckingmechanism is used.

Other objects of the invention will be apparent hereinafter from thespecication and from the recital of the appended claims.

Chucking mechanisms in which the chuck is heldin operative position byspring pressure and is released by hydraulic pressure are in rathercommon use, but full hydraulically operated chucks have heretofore hadonly limited usage. This is due principally to the fact that such ashave heretofore been built have either been complicated in constructionor have lacked means for Aadjusting the chucking pressure to suitdifferent jobs. To properly hold a large, heavy gear in a gearcttingmachine, for instance, there, must be a rather high pressureexerted on the drawbar of the chucking mechanism, but if this samepressure is used, when a gear of thin section isbeing cut, the gear willbe Warped by the chucking pressure and will not be cut accurately.

The problem of adjusting the operating pressure to suit the job isfurther complicated in machines of modern design by reason of the factthat in such machines there arev frequently several diierent' partsoperated by hydraulic pressure. Thus, it is the practice in gear cuttingmachines today to move the work head to and from operating position byhydraulic power,

the work head in operating position by hydraulic power. The powerrequired for these functions determines the pressure at the supply pump,and

determines, therefore, the pressure of the motive 5 iluid that flows tothe chucking mechanism.

Hence a problem is presented, not merely of adjusting the pressure inthe chucking mechanism itself for diierent jobs, but of adjusting thispressure relative to the pressure employedin other parts of the machine.whose pressure is derived from the same source as the chucking pressure.

These diiiiculties have been overcome in chucking mechanisms constructedaccording to the present invention through use of an adjustable reducingvalve in the line that is on pressure when the chucking mechanism is inoperative position. 'Ihis permits of reducing the primary pressure,which is used on the machine and which is required for the operation ofother hydraulic parts of the machine, to a pressure suitable for thechucking requirements. Further than this, by adjusting the reducingvalve, the pressure in the operating line of the chucking mechanism canbe controlled vto suit the particular work which is being operated upon,and a smaller pressure can be employed where the work piece is of thinsection than is used where the work piece is o! heavy section.

The chuck proper ymay be of any suitable construction, but is preferablypiston-actuated. That is, the draw bar of the chucking mechanism ispreferably connected to a piston which is moved in one direction toeii'ect chucking, and in the opposite direction to release the chuck.The reducing valve is incorporated, as already stated, in the line thatis on pressure when the piston is in chucking position.

The reducing valve may be of any suitable construction, but I havedesigned and preferably employ with the chucking mechanism of thepresent invention a reducing valve which is of novel construction. Thiscomprises a balanced valve which is spring pressed in one direction andwhich is vurged in the opposite direction by hydraulic pressure. Thevalve is so constructed that the tension of the spring can be adjusted,and thereby the pressure on the operating side of the chuck-piston canbe controlled. The pressure iluid, which operates the chuck, isdelivered to 50 the chamber in which the reducing valve is mounted, andfrom this chamber it is delivered to the operating side of the piston.The reducing valve controls the ilow of the pressure fluid through thechamber. IThe valve is formed with and' to clamp 55 two spacedpiston-like portions, and the pressure riuid flowing into the valvechamber operates on adjacent opposed faces of the piston-like portionsto produce a balanced eiIect. The coil spring, already referred to,operates on the opposite side of one of these piston-like formations andthe pressure uid operates on the opposite face of the other piston-likeformation. The latter pistonlike formation is connected to the line thatows to the chuck-piston, so that the same pressure is applied to thereducing valve, tending to move it in one direction, as is employed forthe operating pressure of the chuck. The coil spring operates againstthis pressure. A slight leakage serves to bleed the line that suppliesthe pressure fluid which tends to move the reducing valve.

When pressure is applied to the chuck-piston to move the draw bar tooperating position, the chuck-piston is first moved rearwardly in itscylinder to move the chuck to chucking position. Then the pressure onthe chuck-piston builds up. This pressure acting on the one face of thepiston-like formation of the reducing valve forces the valve closedagainst the resistance of the spring. When the pressure on the valve isreduced again, however, through leakaage, the spring forces the valveopen. When the pressure is built up again, the valve is closed. etc. Inactual practice, an equilibrium is established and the desired pressureis maintained on the operating side of the chuck-piston. By simplyadjusting the tension of the spring, then, this pressure can be changedto suit the job being chucked.

In the preferred construction, the chuck-piston is provided with acentrally-disposed bore that extends through it from front to rear, andthe draw-bar passes entirely through this bore, being adjustablyconnected to the piston at the rear end thereof. This construction isespecially advantageous where different type chucks are being used. Itprovides a readily accessible adjustment for adjusting the draw-baraxially relative to the chuck-piston to control the effective length ofmovement of the draw-bar. Pot-chucks, platechucks, collet-chucks, allrequire diierent amounts of movement of a draw-bar to effect chucking.With chucking mechanisms of prior construction, the chuck actuatingparts had to be partially or wholly disassembled to adjust the length ofmovement of the draw-bar, and, if a draw-bar of one length had to besubstituted for a draw-bar of a different length, this same partial ortotal disassembly had to be made. With the chucking mechanism of thepresent invention, the draw-bar can be adjusted from the rear of thework spindle and assembled or disassembled from either front or rear ofthe spindle.

One embodiment of in the drawings in which:

Fig. 1 is a sectional view through the operating end of a chuckingmechanism constructed according to a preferred embodiment of the presentinvention;

Fig. 2 is another sectional view through the operating end of thischucking mechanism but taken along a different line;

Fig. 3 is arear elevation of the operating end of the chuckingmechanism, with partsbroken away; and

Fig. 4 is a diagrammatic view showing how the chucking mechanism of thepresent invention may be connected with a standard control valve on amachine having several different hydraulically actuated parts.

Reference will now be had to the drawings for a more detaileddescription of the invention.

the invention is illustratedr Il denotes the work spindle of the machineon which the chucking mechanism of the present invention is to be used.Il denotes a draw-bar which is connected to the chuck that is employedfor securing the work to this work spindle. The chuck proper does notform any part of the present invention. Sufllce it to say that the chuckis moved to operative position by rearward movement of the draw bar I Iin lthe work spindle It, and the chuck is released by forward movementof the draw bar II in the work spindle Il.

The rear end of the draw bar passesthrough the centrally disposed boreof a piston I2, and the draw bar is adjustably secured to this pistonthrough the medium of a collar I4 and a nipple I5. The collar isthreaded onto the draw bar, and the nipple engages over a flange formedon the collar and threads onto the rearwardly projecting portion I3 ofthe piston. By rotating the collar I4, the draw-bar can be adjustedaxially to adjust its effective length relative to the piston I2 to suitdifferent types of chucks and different work-pieces. Also by rotatingthe collar I4 and nipple I5, the draw-bar can be removed from thework-spindle I0 'either through the front end or the rear end of thespindle. A lock-nut I1 holds the collar in position on the draw-bar.

The piston I2 is mounted to reciprocate in a cylinder or housing 20.'I'his housing is generally cylindrical in shape and has an extension 2Iformed on its rear end which is of reduced diameter and also cylindricalin shape. A ring-like member 22 ts around the extension 2I of thehousing 2G. This member is secured against axial movement relative tothe housing 20 by an end plate 23. The end plate is secured to theextension 2l of the housing by screws 24 (Fig. 3).

The motive uid is supplied to or exhausted from one side of the pistonI2 through a pipe 25. 'Ihis pipe communicates with the bore 26 (Fig. 3)that is formed in the enlarged portion 53 of the ring-like member 22.Ducts 21 and 28 lead from this bore .26. The duct 21 communicates'with acircular groove 29, which is formed in the periph ery of the extension2l of the cylinder 20. The duct 28 communicates with a circular groove3D also formed in the extension 2I of the cylinder 20 and spaced fromthe groove 29. The grooves 29 and 30 communicate through ports 3| and32, respectively, with a duct 33. The grooves 29 and 30 also communicatethrough ports 35 and 38 with the duct 31.

One end of the duct 33 is closed by a plug 33 and in its other end thereis mounted a ball check valve 40. The ball check valve 40 is normallyheld seated by a spring 4I to normally close the duct A33 fromcommunication with the duct 42 that leads into the cylinder 20 in therear of the piston I2.

One end of the duct 31 is closed by a plug 45 and in the opposite endthere is mounted a. ball check valve 46 that is held in normally closedposition by a coil spring 41, thus normally closing communicationbetween the duct 31 and the duct 48 that leads into the cylinder 20 atthe rear of the piston I2. It will be noted that both the duct 42 andthe duct 48 lead to the rear face of the piston I2, but they are atopposite sides of the longitudinal axis oi the piston.

The motive fluid is supplied to and exhausted from the front face of thepiston I2 through the pipe 50 (Fig. 3). This pipe communicates with f lradially disposed ports 5I formed in a sleeve or chamber 52` in whichthe reducing valve 54 is mounted. This sleeve or chamber 52 ts into thebore 26 of the enlarged portion 53 of the ring-like member 22. Thesleeve or chamber 52 is also provided with ports 55. These ports 55communicate with the duct 56 that leads to a circular groove 51 formedon the perlphery'of the extension 2| of the cylinder 28. The groove 51lies between the grooves 29 and 38 and communicates through a port 58with a duct 68. The groove 51 also communicates through a port 59 with aduct 6|.

One end of the duct 68 is closed by a plug 63 and in its opposite endthere is mounted a. ball check valve 64. 'I'his valve is normally heldclosed by a coil spring 65, so as to close communication between theduct 68 and a duct 66. The duct 66 leads to the front der 28.

One end of the duct 6I is closed by a plug 61 and in its opposite endthere is mounted a ball check valve 68. This ball check valve isnormally held closed by a coil spring 69 so as to close oi communicationbetween the duct 6| and a duct 10 that leads to the front end of thecylinder 28.

The ducts 66 and 'i8 are of the shape shown in Fig. 1 and communicatewith the front face of the piston I2 at opposite sides of thelongitudinal axis of the piston l2.

The reducing valve 54 (Fig. 3) is of the balanced type. It has twospaced piston formations and 16 that are connected by a reduced stemportion. The opposedA adjacent faces of the piston-like formations 15and 16 have the same exposed surface area. These piston-like formations15 and 16 control the flow of the motive iluid between the line 58 andthe duct 56.

There is a duct 88 that leads from the duct 56 the under side of thepiston-like formation 16 of the valve 54. Thus the pressure of themotive fluid flowing into the duct 56 is also exerted end of thecylin-rl on the under face of the piston-like formation Y,

16 forcing the valve upwardly in the sleeve 52. A coil spring 8|, whichsurrounds the upper portion of the valve stem, serves to normally pressthe valve downwardly against the pressure exert.. ed by the motive fluidon the under face of the piston-like formation 15. The coil spring 8| isinterposed between the upper face of the pistonlike formation 15 of thevalve and a nut 82. This nut threads adjustably into the bore 26 of thering-like member 22 and it is secured in any adjusted position by alock-nut 83.

The lower end of the sleeve 52 is closed by a cap 85. This cap has ahole 86 drilled in it that communicateswith the duct 88. This hole is ofa sumcient diameter to receive the pin 81.

'I'he hole 86 allows a certain amount of leakage from the duct 88. 'I'heamount of this leakage is determined, of course, by the dlerence indiameter between the hole and the pin 81. The use of the pin 81 preventsthe leakage being stopped by dust or grit, since there is a space allaround the periphery of the pin between the pin and the hole.

'Ihe piston I2 is shown in Fig. 1 in its releasing position. When it isdesired to chuck a work piece on the spindle of the machine on which thechucking is employed, the draw bar II is moved rearwardly by applicationof pressure iiuid to the front face of the piston I2. For this purpose,the line 58 is put on supply. 'I'he pressure fluid then ilows .from theline 58 through the ports 5I and 55 of the sleeve 52, the duct 56, thegroove 51 in the mechanism of the present invention extension 2| of thecylinder 28, and the port 58 into the duct 68. The pressure of themotive iluid forces the ball check valve 64 open against the resistanceof the spring 65, and the motive fluid flows on through the duct 66 tothe front face of the piston I2 to move the piston rearwardly and effectthe chucking operation. At this time, the ball check valve 68 is heldclosed by the coil spring 69 and by the pressure of the motive iluid onthat valve. At this time, also, the motive uid is being exhausted fromthe rear end of the cylinder 28 through the duct 48, the now-open ballcheck valve 46, the ports 35 and 36, the grooves 29 and 38, the ducts 21and 28, the bore 26 and the pipe 25. The duct 33 is at this time closedto exhaust by the ball check valve 48 and by the pressure of the motiveiiuid on this valve.

When it is desired to release the chuck, the line 25 is put on supplyand the line 58 on exhaust. The pressure uid then flows from the line 25through the bore 26, ducts 21 and 28, the grooves 29 and 38, the ports3| and 32, the duct y33, the ball check valve 40, and the duct 42 intothe rear end of the cylinder 28. At this time, the pressure of themotive fluid aids the spring 41 in keeping the ball check valve 46closed. At this time, also, the motive fluid will exhaust from the frontend of the cylinder 28 through the duct 18,. lthe ball check valve 68,the port 59, the groove 51, the duct 56, the ports 55 and 5| of thesleeve 52, and the line 58. The ball check valve 54 is at this time heldclosed by the coil spring 35 and by the pressure of the exhaust uid.

The several ball-check valves 48, 46, 64 and 68 are provided to insuresuflicient operating pres-A sure in the system forthe movements of thepiston I2 and to prevent vibration or chatter. They also serve to keepair from entering into the system where the chucking mechanism standsidle for a relatively long length of time, as, for instance, overnight,and vthey also help to prevent leakage.

The provision of three grooves 29, 51 and 38 in theextension 2| of thehousing 28 balances the pressure on this extension. If only two grooveswere provided, one being onpressure and the other on exhaust there mightbe a tendency of the extension 2| to bind in the ring-like member 22.This would be very serious, for in any gear cutting machine, the workspindle must be rotated periodically for indexing and in a geargenerating machine the work spindle must rotate7 also during cutting,and, where the work spindle rotatesfthe housing 28 and its extension 22must rotate with the spindle. With the construction illustrated, nobinding is possible. If the middle groove 51 is on supply, the twogrooves 29 and 38, at either side of therniddle groove 51, are onexhaust and there is nol cramping of the extension 2| in the ring-likemember 22. Similarly, when the grooves29 and 38 are 3 on supply and thegroove 51 is on exhaust, a balanced eiect will be obtained, and againthere will be no tendency of the extension 2| to be vcramped in thering-like member 22.\ A further advantage of the three grooves 29, 51and '38 is better lubrication of the periphery of the extension 2| whenthe extension is rotating in the ring-like member 22 as is the caseduring indexing of the work spindle or generating rotation thereof. Thering-like member 22 is, of course, secured in any suitable manner to arelatively xed part of the machine.

The function of the reducing valve 54, as al-'fA -the pressure on Ivalve.

ready stated, is to control the amount f chucking pressure. The amountof chucking pressure can be controlled by adjusting the tension of thecoil spring 0| through adjustment of the nut 82. When the line 50 isilrst opened to supply, the pressure in the duct 50 builds up to a pointwhere it is suillcient to move the piston I2 from the position shown inFig. 1 rearwardly in the cylinder 20. After the piston has bottomed inthe left hand end of the cylinder 20, the pressure in the line 56continues to build up. As this pressure builds up, it builds up also inthe duct 80, exerting pressure on the under face 'of the piston-likeformation 18, forcing the valve 54 upwardly against the resistance ofthe spring 8|. This causes the piston formation 16 to close the ports55.- Leakage from the hole 86, however, reduces the pressure on theunder face of the rformation16, and the ports 55 are opened again byaction of the spring 8|. This allows the front face of the piston I2 tobuild up again, andthe ports 55 are again closed by the piston formation16 of the reducing In actual practice, a condition of equilibrium isestablished, and the reducing valve remains open `a constant amountdetermined by the-tension of the spring 8| and by the amount of leakagethat can occur through the hole 86. It will be obvious, then, thatbyvarying the tension of the spring 8|, different pressures on the frontface of the piston I2 can be obtained.

Thus, the chucking pressure can be adjusted to suit the nature of thework which is to be chucked.

When the line 25 is on supplyI and the line 50 on exhaust, the pressureuid flows into the bore 26. The pressure exerted by this liquid on thelupper face of the piston formation 15 serves to hold the reducing valve54 open against any back-pressure exerted by the exhausting liquid onthe loweriace of the piston formation 16.

-For the purpose ofreadily atusting the chucking pressure, a pressuregauge 90 may be provided. This gauge may be of any suitable constructionand may be connected to the groove 51 in the extension 2| by a duct 9|and a pipe 92.

As already stated, one of the advantages of the present invention isthat it permits of employing a chucking pressure different from thepressure at the source of the motive fluid, that through the line 95 tothe clamping mechanism and through the lines |00 and I'0I to themechanism for moving the work head, the amount of chucking pressure willbe controlled by the reducing valve 54. Hence, when the draw bar ismoved to the rear, by rearward movement of the piston I2, to chuck thegear blank G, the amount of pressure on the front face of the piston I2will be determined, as described, by the tension of the spring 0| of thereducing valve 54. It will thus be seen that the chucking pressure maybe different from the pressure used for operating other parts of themachine.

Where the machine is shut down for some time, as for instance,overnight, there may be some leakage from the hydraulic system. It maytherefore be desirable to employ an auxiliary holding means, such as thecoil springs |05 shown in Fig. l, to hold the piston I2 and draw bar inchucking position. These springs are mounted in suitable alignedrecesses formed in the piston I2 and in the cover plate |06 of thecylinder 20v and they are interposed between the piston and the coverplate. The cover plate |06 is secured to the cylinder 20 by screws (notshown). The

work spindle I0 is secured to the cover plate by* a nut |01 that threadsonto the rear end of the work spindle and that is fastened to the coverplate |06 by screws |08. A set-screw |09 serves to hold the nut |01against rotation relative to the work spindle I0.

is, at the pump, and different from the pressure employed in other partsof the machine on which the chucking mechanism is used. Thus, thechucking mechanism may be employed on a gear cutting machine on whichhydraulic pressure is also used for moving the work head to and fromoperative position, and for clamping the work head in operativeposition. In such a machine, it is usual to employ a rotary controlvalve, such as illustrated diagrammatically at 95 in Fig. 4, to controlthe various hydraulic operations.

The pressure fluid may be supplied from the hydraulic pumpv to thechamber 96 of this valve through a line 91. The pressure fluid may beexhaused from the chamber 96 through the line 98. A line 99 may leadfrom the valve chamber to the mechanism for clamping the work head, andlines |00 and |0| may lead from this chamber to the opposite sides ofthe piston that is used for moving the work head between chucking andoperating positions. The lines 25 and 50, which lead to the chuckingmechanism, are also connected to the chamber of this rotary controlvalve 95. It will thus be seen that while the motive fluid at pumppressure maybe supplied A guard I0, shown only in Fig. 3, may beprovided to surround the chuck operating mechanism and to protect thesame. Thisguard may be connected to the chuck operating mechanism in anysuitable manner. Y

As has already been stated, while the reducing valve of this inventionhas been described as used on a chucking mechanism, it will beunderstood that it may be employed in various other connections. Thus,it Ymay be said that while the invention has been described inconnection with a 'particular embodiment thereof and in connection witha particular use therefor, the invention is capable 'of variousmodiilcations and uses, and this application is intendedto cover anyvariations, uses, or adaptations of the invention following, in general,the principles of the invention and including such departures from thepresent disclosure as come within known or customary practice in the artand as may be applied to the essential features hereinbefore set forthand as fall within the scope of the invention or the limits of theappended claims.

Having thus described my invention, claim is:

1. In a chucking mechanism, the combination with a chuck of a cylinder,a piston connected to said `chuck and reciprocable in said cylinder,ducts for conducting motive fluid to and from opposite sidesof thepiston to eiIect movement of the chuck to and from operative position, abalanced reducing valve interposed in the duct that leads to the side ofthe piston which is on supply when the chuck is in chucking position,said valve being adapted to control the pressure in said duct when it ison` supply, a by-pass for conducting uid under pressure from said ductto the valve to urgey said valve in one direction, a spring operativelyconnected to said valve to urge said valve in the opposite direction,whereby said valve operates to maintain a predetermined pressure on thechucking side of said piston when said duct is on supply, and means .for

what I adjusting the tension of said spring to control the amount ofchucking pressure on said piston.

2. In a chucking mechanism, the combination with a chuck, of a cylinder,a piston reciprocable in the cylinder and connected to the chuck, ductsfor conducting the motive uid to and from opposite sides of the pistonto move the chuck to and from operative position, a housing having inletand outlet ports, a valve mounted in said housing to control theconnection between said ports, the duct which is connected to the sideof the piston, that is on supply when the chuck is in operativeposition, being connected to the outlet port of said housing, means forsupplying fluid under pressure to the inlet port of said housing, saidvalve being of the balanced type and having two piston-like portionswhose adjacent opposed faces have the same surface area, a by-passconnecting the duct, which is on supply when the chuck is in operativeposition, with the opposite face of one of the piston-like portions ofsaid valve so that the pressure of the motive uid may urge said valve inone direction, a spring mounted in said housing and operativelyconnected to said valve and tending to move the valve in the oppositedirection, whereby said valve may operate to maintain a predeterminedpressure on said piston when the chuck is in operative position, andmeans for adjusting the tension of said spring totadjust the amount ofsaid pressure.

3. In a chucking mechanism, the combination with a chuck, of a cylinderhaving front and rear end walls, a piston reciprocable in vthe cylinderand provided with a bore extending entirely therethrough, a draw-barsecured at its front end to the chuck and extending through the bore insaid piston and through an opening in the rear end wall of the cylinder,means projecting beyond the rear end erable from the exterior of thecylinder for adjustably securing the draw-bar to the piston at its rearend, and means for exerting pressure selectively on opposite sides ofthe piston to move the draw-bar to or from chucking position.

4. In a chucking mechanism, the combination of a rotary work spindle anda chuck therefor, of a cylinder secured to the work spindle and havingthree parallel spaced grooves formed on its periphery, a pistonreciprocable in the cylinder, a draw-bar secured at its rear end to thepiston and connectible at its front end to the chuck, and means forconducting a hydraulic pressure uid to and from the two sides of thepiston comprising a relatively xed part in which the cylinder isrotatable, a duct in said relatively xed part which leads to the centralgroove of the three grooves formed on the periphery of the cylinder, asecond duct in said relatively xed part which leads to the two endgrooves of the three grooves, means connecting the central groove to oneside of the piston, means connecting the two end grooves to the otherside ot the piston, and a valve controlling supply and exhaust of themotive fluid to the two ducts.

LEONARD O. CARLSEN.

wail of the cynnder and op-

